- 标题
- 摘要
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- 实验方案
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Event-Related Potentials Allow for Optotype-Based Objective Acuity Estimation
摘要： The event-related potential P300 has been proposed for objective acuity estimation. In contrast to the acuity VEP, which relies on grating or checkerboard stimuli, the P300 can be recorded to small stimulus differences, making it suitable to use optotype stimuli. This may result in a better agreement with subjective measures of acuity than that found with VEP-based estimates. We tested the feasibility of using Landolt C optotypes with a P300 acuity paradigm and assessed the relationship between subjective and objective acuity estimates for both optotype and grating stimuli.
关键词： optotype,spurious resolution,event-related potentials,P300,visual acuity,grating,malingering
更新于2025-09-09 09:28:46
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An ultrasonic sensor composed of a fiber Bragg grating with an air bubble for underwater object detection
摘要： We present and experimentally demonstrate a novel optical fiber ultrasonic sensor composed of a fiber Bragg grating (FBG) with an air bubble for underwater object detection. The air bubble is formed by splicing etched FBG and single mode fiber (SMF) with taper-shaped holes. And because of the corrosive action, the diameters of FBG and SMF reduces from 125 μm to dozens of micrometers, which will be conducive to improving the sensor's performances. The experiment results indicate that the sensor has high voltage responses of 6.3 V and 7.1 V to the continuous and pulse ultrasonic wave (UW) at 1 MHz and could be used for underwater objects imaging with high signal-to-noise ratio (SNR). Subsequently, the environmental temperature will not influence ultrasonic measurements using the sensor on account of the low temperature sensitivity of 19.5 pm/°C.
关键词： Ultrasonic sensor,Fibre Bragg grating,Fibre-optic sensor,Underwater object detection
更新于2025-09-09 09:28:46
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A real-time impact detection and diagnosis system of catenary using measured strains by fibre Bragg grating sensors
摘要： This paper describes an impact detection system using strain signals based on fibre optic sensors(FBG) for the real-time monitoring of the catenary system. The proposed detection system consists of three subsystems: a measuring system, a data processing and analysis system, and a status display and data access system. Because the strain signals obey the normal distribution, to monitor the catenary system in real time, a novel method that combines mobile standard deviation with the mobile Pauta criterion is proposed to distinguish real impact from the strain signal background. The use of this adaptive judging method reduces the misjudgment rate of impacts and improves the impact recognition accuracy. These impacts can be identified by the data analysis system, which provides impact location and their causes using the features of the catenary system. This method can simplify the detection system compared with the traditional location method. An application to a commercial metro line system indicated that the impacts on the catenary system were main caused by overlaps, expansion joints or steady arms, and were verified by correspondence with the floor plan of the catenary and manual inspection results. These results verified the reliability and effectiveness of the proposed impact detection system.
关键词： catenary,real-time monitoring,fibre Bragg grating,Impact detection,fault diagnosis
更新于2025-09-09 09:28:46
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Radiation-Induced Effects on Fiber Bragg Gratings inscribed in Highly Birefringent Photonic Crystal Fiber
摘要： The Fiber Bragg Gratings (FBGs) inside Photonic Crystal Fibers having high fiber birefringence, such as in PCF with butterfly shape microstructure, are characterized by two Bragg peaks. The spectral distance between these two peaks is not affected by a change of temperature or by a longitudinally applied strain, but this spectral separation evolves when the sensor is subjected to a transversal strain. This makes such FBGs inscribed in highly birefringent PCFs very interesting for structural health monitoring of civil structures, as well as for operation in harsh environments such as the ones associated with the nuclear industry. In this work, we monitor the Radiation-Induced Bragg Wavelength Shift (RI-BWS) of the punctual sensor and the Radiation-Induced Attenuation (RIA) in the fiber used for its inscription up to a dose of 1.5 MGy(SiO2). Even if we observe a RI-BWS for both Bragg peaks, the spectral distance between them only slightly evolves, of less than 10 pm. These gratings are then very promising sensors for the structural health monitoring of nuclear facilities.
关键词： radiation effects,Fiber Bragg Grating,pressure sensors,Photonic Crystal Fiber
更新于2025-09-09 09:28:46
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Interleaved Silicon Nitride AWG Spectrometers
摘要： Interleaved arrayed waveguide gratings (AWGs) have a great potential in providing large channel counts and narrower channel spacings for many applications, including optical communication, spectroscopy, and imaging. Here, a 75-channel silicon nitride based interleaved AWG was experimentally demonstrated. The design is comprised of a 3-channel primary AWG with 1 nm of resolution and three 25-channel secondary AWGs each with 3 nm of resolution. The final device has a spectral resolution of 1 nm over 75 nm bandwidth centered at 1550 nm. Its performance is compared with a conventional AWG spectrometer with 75 nm of bandwidth and 1 nm of resolution. The interleaved AWG demultiplexer showed lower crosstalk and better uniformity in addition to being two times smaller than the conventional design.
关键词： interleaver,C-band,arrayed waveguide grating,silicon nitride,demultiplexer,Integrated optics
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Modeling and Analysis of SOI Grating Coupler for Bio-sensing Applications
摘要： This work presents, analysis of SOI optical grating structure operating at 1310 nm wavelength. Power coupling analysis between optical source and grating structure is done. The maximum power coupling efficiency of 55.2% is achieved for 500nm grating pitch having 50% duty cycly on 220nm Si-layer.
关键词： Broadband wavelength,Injection angle,Grating coupler,Multi beam,bio-sensor
更新于2025-09-05 23:14:25
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High-Speed and High-Resolution Interrogation of a Strain and Temperature Random Grating Sensor
摘要： High-speed and high-resolution interrogation of a random fiber grating sensor based on spectral shaping and wavelength-to-time (SS-WTT) mapping, and pulse compression for simultaneous measurement of strain and temperature is proposed and demonstrated. In the proposed system, an ultrashort pulse is spectrum shaped by a high-birefringence (Hi-Bi) random grating (HBRG) to generate two orthogonally polarized spectra with a wavelength difference determined by the birefringence of the HBRG, which are then fed to a dispersive optical loop in which a linearly chirped fiber Bragg grating (LCFBG) is incorporated, to perform linear WTT mapping, to generate two temporally separated optical pulses, which are converted to two random electrical waveforms at a photodetector). Random pulse compression is then performed to increase the interrogation resolution. By measuring the time shifts of the temporally compressed pulses, the strain and temperature information is retrieved. An experiment is performed. The experimental results show that the proposed random grating sensor and its interrogation system can provide a strain and temperature resolution of 7.1 με and 0.79 °C at an ultrahigh speed of 20 MHz.
关键词： linearly chirped fiber Bragg grating,Fiber Bragg grating,interrogation,sensor
更新于2025-09-04 15:30:14
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Comparison between Grating Imaging and Transient Grating Techniques on Measuring Carrier Diffusion in Semiconductor
摘要： Optical grating technique, where optical gratings are generated via light inference, has been widely used to measure charge carrier and phonon transport in semiconductors. In this paper, compared are three types of transient optical grating techniques: transient grating diffraction, transient grating heterodyne, and grating imaging, by utilizing them to measure carrier diffusion coefficient in a GaAs/AlAs superlattice. Theoretical models are constructed for each technique to extract the carrier diffusion coefficient, and the results from all three techniques are consistent. Our main findings are: (1) the transient transmission change ΔT/T0 obtained from transient grating heterodyne and grating imaging techniques are identical, even these two techniques originate from different detection principles; and (2) by adopting detection of transmission change (heterodyne amplification) instead of pure diffraction, the grating imaging technique (transient grating heterodyne) has overwhelming advantage in signal intensity than the transient grating diffraction, with a signal intensity ratio of 315:1 (157:1).
关键词： diffraction,Transient grating heterodyne,grating imaging,carrier diffusion
更新于2025-09-04 15:30:14
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MEMS-based Tunable Grating Coupler
摘要： We demonstrate a microelectromechanical-system-based tunable grating coupler capable of changing the central wavelength. The grating structure is fabricated on a suspended cantilever with supporting arms and can be tuned by an applied voltage. We demonstrate a tunable range of 22.8 nm under actuation voltages of up to 12 V in the present devices. In addition, we show that the supporting arms are critical components that can be used to effectively avoid the pull-in effect.
关键词： MEMS-based tunable grating,Silicon photonics,grating coupler
更新于2025-09-04 15:30:14
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An Open-Source Artificial Neural Network Model for Polarization-Insensitive Silicon-on-Insulator Subwavelength Grating Couplers
摘要： We present an open-source deep artificial neural network (ANN) model for the accelerated design of polarization-insensitive subwavelength grating (SWG) couplers on the silicon-on-insulator platform. Our model can optimize SWG-based grating couplers for a single fundamental-order polarization, or both, by splitting them counter-directionally at the grating level. Alternating SWG sections are adopted to reduce the reflections (loss) of standard, single-etch devices—further accelerating the design time by eliminating the need to process a second etch. The model of this device is trained by a dense uniform dataset of finite-difference time-domain (FDTD) optical simulations. Our approach requires the FDTD simulations to be made up front, where the resulting ANN model is made openly available for the rapid, software-free design of future standard photonic devices, which may require slightly different design parameters (e.g., fiber angle, center wavelength, polarization) for their specific application. By transforming the nonlinear input–output relationship of the device into a matrix of learned weights, a set of simple linear algebraic and nonlinear activation calculations can be made to predict the device outputs 1,830 times faster than numerical simulations, within 93.2% accuracy of the simulations.
关键词： subwavelength devices,machine learning,Silicon photonics,polarization insensitivity,grating couplers,artificial neural networks
更新于2025-09-04 15:30:14